The long-term objectives are to make correlated studies of facial form and masticatory function in the presence of experimental variables, and to formulate from these studies new concepts for the diagnosis and treatment of severe malocclusion and jaw dysfunction. Alterations of facial growth and masticatory function will be produced experimentally in monkeys by means of mechanical forces and experimental brain lesions. Documentation of changes in form will be cephalometric and histologic, function will be studied by mandibular tracking combined with EMG analysis. Paralleling these experiments will be descriptive studies on postorthodontic growth patterns, on TMJ patients, and control human subjects. In the studies of growth on humans, experimental variables will include different orthodontic procedures, such as serial extraction and slow palatal expansion; in the functional studies these will include local anesthesia, application of loading forces to the mandible, occlusal equilibration, and the transition from deciduous to permanent dentition. The methodology for recording and analyzing data on mandibular movements and EMG activity will rely upon computer storage and programming techniques designed to assist in diagnostic analysis and evaluation of treatment responses.